This invention relates to turbines and to other such devices capable of interacting with a flow of a liquid medium such as a flow of water in such a manner as to transfer energy from the liquid medium/water to means for utilising the transferred energy such as a mechanically driven device.
It is known to use turbines and rotating machinery for the purpose of extracting energy from moving water currents, for example such as has been disclosed in our British Patents GB 2311566 “Column Mounted Water Current Turbine”, GB 2348250 “Pile Mounted Vertically Displaceable Water Turbine”, and in GB 2347976 “Variable Pitch water turbine”.
In these patents we have disclosed constructions pertaining to water driveable turbines where one or preferably two or more turbines and associated rotors may be arranged such that they are supported on a structure embedded in, or carried on a foundation set, in the sea, river or estuary bed.
We have also disclosed similar relevant information in foreign patents derived from the above mentioned British patents, including among others, U.S. Pat. No. 6,652,221, European EP 1183463, New Zealand NZ 514274 and Australian AU 766741, all entitled “Water Current Turbine Sleeve Mounting”. There are also a few examples of such prior art from other sources.
It is also known how to construct devices capable of absorbing energy from passing waves. Said devices may use several physical principles in that they may either react to surface movements of the waves, for example: by displacing air in a chamber engaged with the surface of the sea through a turbine, such a device being commonly known as an “oscillating water column”, by reacting wave induced buoyancy forces in some way such as, for example, to generate high pressure in a hydraulic ram which in turn can be utilised to power a hydraulic motor capable of driving a generator or by making use of static pressure variations arising from the varying height of the water surface caused by passing waves.
Some wave power devices can use resonance effects as well as in some cases buoyancy forces arising in heave caused by passing waves to enhance their efficiency at extracting energy from waves.
It should be noted in practice said water driveable and wave driveable devices will generally be connected mechanically, hydraulically or pneumatically to a power train capable of absorbing the available energy from the relatively slow movement of the device in response to slow moving water movements, and converting such energy to a more usable form such as electricity or pressurised fluid which may be readily respectively transferred by way of cables or pipes to a point of application where it may usefully be exploited.
Said power train may typically consist of a geared speed increaser coupled to an electrical generator or to a hydraulic pump or in some cases the rotor may be directly coupled without recourse to a mechanical speed-increaser to a specially designed and matched slow-speed generator or pump.